Basically a controller is designated as a device which can provide multiple axis outputs, or multiple measurements using load cells. These devices, for example, can be used in fly by wire systems, which require very high reliability, limit and ultimate load, and safety margin. Such fly by wire systems utilize a controller which basically is a multiple axis or multiple measurement load cell, the pilot manipulates the controller by twisting it to the right or the left and moving it up and down. In this manner, a twist to the left would indicate a left turn for the aircraft, a twist to the right would indicate a right turn. The movement up and down, would indicate a pitch or a roll. In any event, such devices are known. These devices are similar to joysticks which basically have an elongated shaft or control rod, which rod or shaft is manipulated in x or y direction and can provide a 360° movement, whereby the sensor produces an output based on the position of the rod. See the above noted co-pending application entitled “Joystick Sensor Apparatus”. Joystick sensors have been used for steering controls for helicopters and other aircraft as well as in many other applications. Thus the above noted application entitled “Joystick Sensor Apparatus” is incorporated herein in its entirety.
In any event, this controller employs load cells which are optimized for multiple axis or multiple measurements. The load cell design typically includes maximizing the output of the strain gages while also maximizing the safety factor, especially for flight control load cells. As indicated, flight control load cells are typically used on fly by wire systems, which require very high reliability, limit and ultimate load, and safety margins. In optimizing a load cell for torsion measurement, the axial output on the same beam will be very low. Reversing the design, optimizing for axial tension/compression gage output, results in a much thinner beam, which will fail under torsion conditions. The instrumented devices for an axial-torsion multiple measurement load cell must be decoupled to eliminate this problem. Various schemes for decoupling include two load cells in series. The problem arises, for the design of the axial load cell section, which is typically also exposed to the torsion inputs. The axial section must be designed such that the axial output is adequate, while preventing failure due to torsion.
This has been a serious problem in the prior art as it is desirable to provide a multiple axis load cell in which the axial and torsion measurements are decoupled, while maximizing the output of both measurements and providing adequate robustness and adequate safety margins for the entire structure.